1. Field of the Invention
The present invention relates to a recording/reproducing apparatus for a writable optical storage medium, and in particular to the optimization of writing parameters (for example, a writing light power, writing beam profile (or, writing strategy)) for writing of a writable optical storage medium, based on experimentally determined optimum test writing parameter for the writable optical storage medium according to the manufacturer thereof, by associating data indicative of the manufacturer of a writable optical storage medium and optimum test writing parameters corresponding to the medium manufacturer, and prior to writing an input signal into a writable optical storage medium, judging the medium manufacturer corresponding to a writable optical storage medium, setting the optimum test writing parameters corresponding thereto, and accordingly determining optimum writing parameters for the medium based by performing an optimization produce employing the thusly set optimum test writing parameters.
2. Description of the Background Art
FIG. 1 illustrates the construction of a conventional writable optical storage medium recording/reproducing apparatus which includes an A/D converter 20 converting an inputted analog signal into a digital signal, a MPEG encoder 30 encoding the digital signal from the A/D converter 20 into a MPEG format signal, a digital writing signal processing unit 70a converting the encoded signal into a writable format by adding an error correction code (ECC), channel bit encoder 80 for converting the signal converted into a writable format into a bit stream, a LC (Laser Diode) driving unit 81 receiving the signal from the channel bit encoder 80 and outputting an optical content driving signal, a pick-up unit 11 writing the input signal into the writable optical storage medium 10 or detecting the written signal in accordance with the optical content driving signal, a drive unit 90 driving the pick-up unit 11 and a spindle motor 91, an R/F unit 100 receiving a signal detected by the pick-up unit 11 and a spindle motor 91, an R/F unit 100 receiving a signal detected by the pick-up unit 11 and outputting a filtered and shaped signal, a servo unit 110 controlling the driving operation of the drive unit 90 based on a tracking error signal TE of the pick-up unit 11, a focus error signal FE, and a rotation of the writable optical storage medium 10 and detecting a synchronous state of the output signal from the R/F unit 100, a digital reproducing signal processing unit 70b recovering a compression write data from the filtered and shaped signal based on the detected synchronous signal, an MPEG decoder 120 decoding the compressed data, converting it into a video and audio signal and outputting the same, and a microcomputer 60 controlling the operations of the recording/reproducing apparatus.
The operation of the writable optical storage medium recording/reproducing apparatus will be explained with reference to the accompanying drawings.
First, when a signal KEYSIG is inputted into the microcomputer 60 requesting a writing operation of an inputted signal INPUT applied to the input terminal, the microcomputer 60 controls the pick-up unit 11 via the servo unit 110 and the drive unit 90 so that a writing light power value Pind written on the writable optical storage medium 10 is read-out before the input signal INPUT is written into the writable optical storage medium. In the case that the writable optical storage medium 10 is a rewritable medium such as a compact disc rewritable (CD-RW), as shown in FIG. 2, the writing light power value Pind is written in a data form of 3 bits W1, W2 and W3 at a M1 information byte of a special information field in an Absolute Time In Pre-Groove (ATIP) signal format of a lead-in region of the writable optical storage medium 10.
When the light power value Pind is read out from the data W1, W2 and W3, the microcomputer 60 outputs test digital data (for example, 101010. . . ) to the channel bit encoder 80 via the digital writing signal processing unit 70a, and the channel bit encoder 80 converts the digital bit stream outputted from the digital writing signal processing unit 70a into a signal format for writing into the writable optical storage medium 10 and then applies the converted signals to the LD driving unit 81.
As shown in FIG. 3, the microcomputer 60 variably applies an adjusting signal to the LD driving unit 81 so that the magnitude of the light power value is changed in a certain range of Pref+a, Pref−a based on a reference writing light power (for example, Pref=8 mW) generated by the writing light power value Pind. The LD driving unit 81 outputs a test digital data based on the optical driving current corresponding to the adjusting signal, and the pick-up unit 11 writes the test digital data into the test writing region of the writable optical storage medium 10. Here, in the case that the loaded writable optical storage medium 10 is a rewritable medium such as a CD-RW, as shown in FIG. 4A, the test writing region is formed in the PCA (Power Calibration Area). In particular, as shown in FIG. 4B, the microcomputer 60 causes the test digital data to be written into the test writing region of the rewritble optical storage medium and writes a certain information into the count region B of the PCA region so that the written number of the test digital data is recognized by controlling the pick-up unit 11.
As the LD driving current is gradually varied, in a state that the test digital data is written in the test region A and the written number of data in the region A is written in the count region B of the PCA of the writable optical storage medium 10, the microcomputer 60 controls the pick-up unit 11, and the pick-up unit 11 reads out the test data written in the test region of the PCA region. The microcomputer 60 causes the R/F unit 100 to filter and shape the reproduced signal read-out by the pick-up unit 11 and continuously detects the jitter amount of the clock signal which is phase-synchronized to the reproducing signal by the servo unit 110. The microcomputer 60 detects an optimum writing light power(in FIG. 3, Pop) by which the test digital data is written at the time when the minimum jitter amount is detected from the clock signals.
When the optimum writing light power Pop is determined, an analog signal such as an externally inputted video or audio signal is inputted into the A/D converter 20 for a writing operation at the writable optical storage medium 10. In this state, the A/D converter 20 converts the inputted signal into a digital signal, and the MPEG encoder 30 encodes the digital signal based on the MPEG method. The digital writing signal processing unit 70a generates an error correction code (ECC) block by adding an encoding and error correction parity to the encoded signal in order to enhance reliability when writing the encoded signal into a writable optical storage medium 10 and output the generated code to the channel bit encoder 80. The channel bit encoder 80 converts the digital bit stream data outputted from the digital writing signal processing unit 70a into a pulse width-modulated signal format for being written into a writable optical storage medium 10.
Therefore, the microcomputer 60 controls the LD driving unit 81 using an optimum light driving current so that the pulse width-modulated signal is written into the writable optical storage medium 10 based on the optimum writing light power detected during the above-described operation. The LD driving unit 81 applies the pulse width-modulated signal to the pick-up unit 11 based on the optimum light driving current, and the pulse width-modulated signal is written in a user's data recording region of the writable optical storage medium 10.
However, in the case that an optimum writing light power is detected, and an input signal is written, a certain light power deviation occurs between the writable optical storage medium fabrication apparatus and the recording/reproducing apparatus, which writes an input signal into the writable optical storage medium and reproduces the signal therefrom, due to a circuit characteristic and a writable optical storage medium characteristic in the system. For example, a certain deviation may occur between a reference light power adapted to the writable optical storage medium in view of the writable optical storage medium fabrication apparatus and the reference light power for determining a writing light power of the writable optical storage medium in view of each recording/reproducing apparatus. The reference light power adapted under the optimum writing condition when fabricating the writable optical storage medium may not correspond to the reference light power which provides the optimum writing conditions for the recording/reproducing apparatus due to the above-described deviation. The optimum writing condition measured when fabricating a certain writable medium may be, for example, a reference light power value of 5 mW. However, in view of the recording/reproducing apparatus, the optimum writing condition with respect to the above-described medium may be a light power value of 11 mW. In this case, even when performing the optimum writing optical detection process by varying the light power value based on the reference light power value of 5 mW, since the steps (for example, 15 steps of increments 0.3 mW) for varying the light power value is limited, in view of the recording/reproducing apparatus, it is impossible to reach 11 mW which is the optimum writing condition of the writable optical storage medium.
Therefore, when fabricating the writable optical storage medium, even when the optimum optical writing power detection process is performed based on the reference light power set during a writable optical storage medium manufacturer, the recording/reproducing apparatus does not detect the optimum writing light power.